Power Macintosh 7500 thinks it's an 8500

[Matlaw]

Hi, after trying to clean very stubborn flux residue the Gestalt ID changed from 68 to 69 and now every software displays the wrong Macintosh model. Before the disassembly, isopropyl soaking and scrubbing it was showing the correct ID.
Tried resetting the Cuda chip, starting with and without the PRAM battery and no dice
There are no schematics for the TNT architecture, so I can't check if it's the matter of a short, missing resistor or something else.
Can the Gestalt ID be software controlled? I really hope I didn't screw up anything on the board. Thanks in advance for any help

 

[Phipli]

Hi, after trying to clean very stubborn flux residue the Gestalt ID changed from 68 to 69 and now every software displays the wrong Macintosh model. Before the disassembly, isopropyl soaking and scrubbing it was showing the correct ID.
Tried resetting the Cuda chip, starting with and without the PRAM battery and no dice
There are no schematics for the TNT architecture, so I can't check if it's the matter of a short, missing resistor or something else.
Can the Gestalt ID be software controlled? I really hope I didn't screw up anything on the board. Thanks in advance for any help

Did you plug something into the LED header on the board?

That is what tells the computer if it is a 7500 or 8500.

 

[Matlaw]

Did you plug something into the LED header on the board?

That is what tells the computer if it is a 7500 or 8500.

I didn't plug the LED back in, because I'm trying to model a new LED holder (gotta love old ABS+FR).
So that's what the loop's for.
Thank you, thank you so much and gosh, now I feel stupid

 

[Phipli]

I didn't plug the LED back in, because I'm trying to model a new LED holder (gotta love old ABS+FR).
So that's what the loop's for.
Thank you, thank you so much and gosh, now I feel stupid

Yup, exactly that. That is what the loop is for.

By the way, the 9600 schematic is available, which is mostly the same as your board. References are going to be different and the video / AV stuff isn't there, and it has two Bandit chips etc etc, but it is the same TNT style platform.

https://www.macdat.net/files/pdf/apple/schematics/apple/powermac_9600.pdf

 

[joevt]

Read F301A000 in Open Firmware.

F301A000 rw@ 4 u.r

The BoxID bits are bit 11 and 12 (where bit 0 is the LSB).

From LSB on the right to MSB on the left, the bits are:
1,0   = 10 : PCI1PRSNT2A_I,PCI1PRSNT1A_I (00=7.5W, 01=15W, 10=25W, 11=No connection)
3,2   = 00 : PCI1PRSNT2B_I,PCI1PRSNT1B_I (00=7.5W, 01=15W, 10=25W, 11=No connection)
5,4   = 10 : PCI1PRSNT2C_I,PCI1PRSNT1C_I (00=7.5W, 01=15W, 10=25W, 11=No connection)
6     = 1  : GCRTSA_I (RTS from SCC modem port of GC to DS8925 ; RTS is a signal that enables TXD± )
7     = 1  : GCRTSB_I (RTS from SCC printer port of GC to DS8925 GeoPort transceiver IC or LocalTalk™ Dual Driver/Triple Receiver )
8     = 1  : factory tests (active low) (emmo) (Serial Test Manager)
9     = 1  : MicSense_I = (connecting long PowerTalk Microphone doesn't change this on my pm8600? What does?)
10    = 0  : ETH10BT_LINK = 0 connected, 1 = not connected (I tested this on my pm8600)
12,11 = 01 : BoxID(1),BoxID(0); 00 = pm9500? 01 = pm8500?
13    = 0  : IO1_PU composite video out (active low) (sixty6) (1 on pm9500)
14    = 1  : IO2_PU fast SCSI (active high) (mesh)
15    = 1  : IO3_PU unused (pulled high)